Extrusion head for plastics extruder

ABSTRACT

The extrusion head for plastics extruders includes a die head, which is disposed axially in the extrusion direction downstream from a jaw plate. The die head is divided in an at least approximately radial direction into a main part and an orifice part and the cones of the orifice part can be fixed independently of one another at the respectively adjacent cones of the main part and exchanged for other cones in a rapid operation.

BACKGROUND OF THE INVENTION

The invention relates to an extrusion head for plastics extruders with adie head, which is disposed axially in the extrusion directiondownstream from a jaw plate and formed by an outer cone and an innercone.

If after a product is extruded, the plastics extruder is to be used forthe extrusion of a different product, particularly one having differentdimensions, it is necessary to change either the entire extrusion head,which is extremely heavy and difficult to handle, or at least the diehead of the extrusion head. In both cases, a considerable effort isinvolved and the extruder generally has to be stopped for several hours.In order to avoid that the plastic material, which is in the extruderand was used for the preceding production, solidifies and clogs theunits of the extruder in contact with the plastic material and evenmakes them inoperable, the extruder, before the actual exchangingprocess, must be operated with a special plastics composition, which isnot flammable, does not degrade and cannot solidify and, in addition,has advantageous heating and thermal conductivity properties.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an extrusion head, which canbe installed quickly and with little effort for extruding a differentproduct.

The inventive extrusion head makes it possible to retool for extruding adifferent product in an exceptionally short time, so that it is notnecessary to use a special plastic material in preparation for theexchanging work. The retooling or installing process is exceptionallysimple and dispenses with the necessity to handle heavy parts. Since theorifice part has only a relatively low mass, it can be brought to theoperating temperature quickly and with little expenditure of energy. Thework of preparing the orifice part removed for later re-use is alsorelatively slight.

Numerous further details and advantages arise out of the followingdescription and the drawing, in which an example of the object of theinvention is shown in greater detail in the accompanying drawings.

FIG. 1 shows an axial section illustrating the jaw plate and the diehead of the inventive extrusion head,

FIG. 2 shows half of a front view corresponding to FIG. 1,

FIGS. 3 and 4 show representations, similar to that of FIG. 1, of amodified version, and

FIG. 5 shows a side view of accessory equipment for exchanging.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to FIG. 1, the inventive extrusion head, which is shown onlydiagrammatically in FIG. 5 and labeled 1 as a whole, comprises a diehead 2 which, in the extrusion direction 4, is disposed axially after ajaw plate 3 and, in detail, is formed by an outer cone 5 and an innercone 6. The outer cone 5 and the inner cone 6 together form the outsideand the inside respectively of a manifold 7, through which the plasticresin composition, which is to be extruded is pressed, before it emergesfrom the manifold 7 in the form of a cylindrical pipe at 8, for example.

The die head 2 is divided in the radial direction into a main part 9 andan orifice part 10. In the example shown, the main part 9, in turn, isdivided in the radial direction into a basic part 11, adjacent to thejaw plate 3, and an intermediate part 12, which is placed between thebasic part 11 and the orifice part 10.

The outer cone 5a of the orifice part 10 is fixed separately at theouter cone 5b of the intermediate part 12, by means of a bayonet-likequick release fitting 13 in the example shown. The quick release fitting13 comprises a sealing and clamping ring 15, which can be secured inposition at the outer cone 5b of the intermediate part 12 by connectingscrews 14 and, at the outer cone 5a of the orifice part 10, forms aclamping gap 17, which is bounded at the front by the sealingprojections 16 and can be changed by the connecting screws 14 and isintended to accommodate the locking projections 18, which arecoordinated with the sealing projections 16. The clamping gap 17 has adiameter, which slightly exceeds the diameter of the circlecircumscribing the locking projections 18 at the outer cone 5a of theorifice part 10, so that the outer cone 5a is accommodated in theclamping gap 17 so that it can be adjusted radially to a limited extent.Its precise radial position is specified with the help of adjustingscrews 19, which pass radially through the sealing and clamping ring 15and engage the annular clamping gap with the end of their threaded bolt.By loosening the connecting screws 14 and rotating the outer cone 5a ofthe orifice part 10 relative to the sealing and clamping ring 15, untilthe locking projections 18 are aligned with the gaps between the sealingprojections 16, the outer cone 5a of the orifice part 10 can be releasedquickly and simply for removal. In the same manner, a different outercone 5a with different dimensions, a different shape, other fittingsand/or of different materials can be put in place rapidly and simply fora different product and locked by rotating and secured by tightening theconnecting screws.

In the embodiment of FIG. 1, the inner cone 6a of the orifice part 10 isseated, in the operating position shown, directly on a central guidingpart 20 and is secured in position at the adjacent inner cone 6b bymeans of a central cap screw 21, which can be screwed down on theguiding part 20. The guiding part 20 is formed by a central spindle,which has an internal thread at the orifice end and can be screwed bymeans of an external thread into the inner cone 6b of the intermediatepart 12 and extends approximately over half the length of the inner cone6a of the orifice part 10. To remove the inner cone 6a of the orificepart 10, it is merely necessary to loosen the cap screw 21, whereuponthe outer cone 6a can be pulled off quickly and easily in the axialdirection and replaced by a different one.

For the design of the extrusion head of FIGS. 3 and 4, the attachment 40is disposed on the guiding part 20. In the interior, the attachment 40is provided with electrical heating elements 41, with which the innercone 6a of the orifice part 10 can be heated. Guided by the outside ofthe sleeve-shaped attachment 40, the inner cone 6a can be placed on theorifice part 10. Such a construction has the advantage that electricalconnections to the heating element 41, which are a component of theguiding part, do not have to be disconnected when the inner cone 6a isexchanged.

By fixing the cones 5a, 6a of the orifice part 10 to the cones 5b, 6b,adjacent to it, of the intermediate part 12 in the manner describedabove, it is possible, in a rapid and simple manner, to retool or set upthe die head 2 for a different product. For this purpose, for example,the inner cone 6a of the orifice part 10 can be exchanged by itself inorder, for example, to produce a pipe or similar extrudate having thesame external dimensions but a smaller or larger wall thickness. Byexchanging only the outer cone 5a of the orifice part, a pipe or thelike can be produced with larger external dimensions and a larger wallthickness. On the other hand, by exchanging both cones 5a, 6a of theorifice part, extrudates with external dimensions, varying within acertain range, and internal dimensions, selected for the externaldimensions, can be produced. The weight of the cones 5a, 6a of theorifice part 10 is relatively low, being of the order of about 5% orless of the weight of the die head, which otherwise is usuallyexchanged, so that only slight energy losses are associated with theexchanging process. The relatively small and lightweight parts caneasily be magazined in a space-saving manner and cleaned quickly andreadily and prepared for later re-use. One or both cones of the orificepart 10 can be exchanged within a few minutes, so that the exchangingprocess can be carried out without the use of a special plasticscomposition, which previously was unavoidable for implementingexchanging processes. As a result of the rapid exchanging process, theproduction of the new product of different dimensions can be commencedwith the plastic material already used previously for extrusionprocesses and present in the extruder. As a result, the productivity ofthe plastics extruder is improved appreciably.

The division of the main part 9 of the die head 2 into a basic part 11and an intermediate part 12 expands the spectrum of the possibledimensional changes due to the possibility of being able to undertakeexchanging processes, which include the cones 5b and 6b of theintermediate part 12, in addition to the exchanging process involvingthe orifice part. If there is a need for it, a further range ofdimensions can be covered by radially dividing the die head 2 twice,since different combinations of the cones of the intermediate part 12can be assigned in each case to different cone combinations of theorifice part 10. A threaded connection may be provided between the innercones 6b and 6c at the location 44 shown in FIG. 1. Also the inner cone6b may be removably attached to the inner cone 6c by the threaded member46 shown in FIG. 4. If such a broad spectrum of dimensional changes isnot required, one division of the die head 2 into a main part 9 and anorifice part 10 is sufficient.

In the case of the examples shown, the outer cone 5b of the intermediatepart 12 and the outer cone 5c of the basic part 11 are connectedtogether by a clamping ring 22, which embraces adjacent conical clampingflanges 23, 24 at the outer cones 5b and 5c of the die head parts 11, 12and advisably is formed by two half parts 25, 26, which can be connectedat one end by a clamping screw 27, which is illustrated only by itsaxial line, and are connected at their opposite end by a joint (notshown), which permits unfolding in the radial direction when theclamping screw 27 is loosened. By opening the clamping ring, the diehead parts 10 and 12 can be removed together rapidly and simply from thedie head part 11 and replaced by other die head parts of differentdimensions. This procedure can also be carried out within minutes. Forthis purpose, a connecting sleeve 28, assigned to the sealing andclamping ring 15, enables load-lifting means to be connected and tofacilitate the process of removing the die head parts 10, 12 jointly.

Instead of the clamping ring connection, the outer cones 5b and 5c canalso be connected by bayonet-like quick release fittings. Preferably,the construction of this fitting is similar to that, which connects theouter cones 5a and 5b. Finally, the outer cones 5a and 5b or 5b and 5ccan also be connected together by permanent magnets, which can bemagnetized and demagnetized by electrical pulses.

The inner and outer cones 5a, 6a of the orifice part 10 are advisablyeach provided with suitable coupling means for connection to asupporting or gripping part of accessory equipment for exchanging, whichis labeled 29 as a whole in FIG. 3. As coupling agent at the outer cone5a of the orifice part 10, a number of countersunk boreholes 30,distributed over the periphery, or a connection plate 30, the edge ofwhich is provided with recesses may, for example, be provided. Theboreholes or recesses can be engaged by appropriate elements of asupporting or gripping part 31, which is provided in the accessoryequipment for exchanging 29 for handling the outer cone 5a of theorifice part 10. As coupling agent for a supporting or gripping part 32of the accessory equipment 29 for exchanging, intended for handling theinner cone 6a of the orifice part, the inner cone 6a can be providedwith undercut coupling openings 33, which are accessible from the front,or also with a ring shoulder 33', which can be gripped from behind andprotrudes over the front side of the inner cone 6a, so that the innercone 6a, as well as the outer cone 5a of the orifice part 10, can behandled fully mechanically with the help of the accessory equipment 29for exchanging. The two operations can be carried out individually aswell as together. In the case of the example shown, the accessoryequipment 29 for exchanging is supported on a movable carriage 34 andcomprises the guides 35, 36 for moving the parts 31, 32 parallel to thecentral axis of the extrusion head 1. The shifting motions can befacilitated by a pressure medium driving mechanism. This is advantageousparticularly when, after the clamping ring 22 is loosened, the two diehead parts 10, 11 are to be removed together and replaced by exchangeparts.

We claim:
 1. An extrusion head for plastics extruders comprising a die head having a longitudinal axis, said die head having a longitudinal main part and a longitudinal orifice part, each of said parts having an inner cone and an outer cone, a first connector connecting said outer cone of said orifice part to said outer cone of said main part, a second connector connecting said inner cone of said orifice part to said inner cone of said main part independently of said first connection such that said outer and inner cones of said orifice part are replaceable on the respective outer and inner cones of the main part independently of one another, said main part including a base part and an intermediate part, said intermediate part being disposed between said base part and said orifice part, said outer cone of said main part including an outer cone section on said base part and an outer cone section on said intermediate part, said inner cone of said main part including an inner cone section on said base part and an inner cone section on said intermediate part, and third connector means connecting said outer cone section of said intermediate part to said outer cone section of said base part such that said outer cone section of said intermediate part is replaceable on the outer cone section of the base part.
 2. An extrusion head according to claim 1 wherein said inner cone of said orifice part, said inner cone section of said intermediate part and said inner cone section of said base part have concentric projections to effect axial alignment thereof.
 3. An extrusion head according to claim 1 wherein said second connector includes a central screw connection having a central longitudinal axis for connecting said inner cone of said orifice part and said inner cone section of said intermediate part in axial alignment.
 4. An extrusion head according to claim 1 wherein said second connector includes a central guiding part and a central cap screw threaded to said guiding part.
 5. An extrusion head according to claim 4 wherein said guiding part comprises a central spindle having an orifice end and inner thread on said orifice end and said spindle having an outer thread threaded to said intermediate part.
 6. An extrusion head according to claim 4 further comprising an attachment on the inner cone of said orifice part and an internal heater on said attachment disposed between said attachment and said guiding part.
 7. An extrusion head according to claim 1 further comprising an adjustment means operably disposed between said outer cone of said orifice part and said outer cone of said intermediate part for effecting radially relative movement between said outer cone of said orifice part and said outer cone of said intermediate part.
 8. An extrusion head according to claim 1 wherein said first connector comprises a bayonet connector.
 9. An extrusion head according to claim 8 wherein said bayonet connector includes a clamping ring, threaded fasteners fastening said clamping ring to said intermediate part, said clamping ring having first locking projections, a clamping gap between said first locking projections and said main part, second locking projections on said orifice part, said second projections being receivable in said clamping gap, said clamping gap having an outer diameter greater than the outer diameter of said second projections on said orifice part to provide for relative radial movement between said outer cone of said orifice part and said outer cone of said intermediate part by loosening said threaded fasteners.
 10. An extrusion head according to claim 1 further comprising a radially disposed threaded adjusting device mounted on said main part and operable to engage said main part to effect radial relative movement between said main part and sad orifice part when said threaded adjusting device is rotated.
 11. An extrusion head according to claim 1 wherein said third connector is operable to be connected and disconnected independently of said first connector and independently of said second connector such that said outer cone section of said intermediate part is replaceable on said outer cone section of said base part independently of said first and second connections.
 12. An extrusion head according to claim 1 further comprising a fourth connector connecting said inner cone of said intermediate part to said inner cone of said base part independently of said third connector such that said inner and outer cones of said intermediate part are replaceable on said base part independently of one another.
 13. An extrusion head according to claim 1 wherein said third connector includes a clamping ring which embraces clamping flanges on said base part and on said intermediate part.
 14. An extrusion head according to claim 11 wherein said third connector comprises a bayonet connector.
 15. An extrusion head according to claim 1 wherein said first connector comprises electromagnetic means.
 16. An extrusion head according to claim 1 wherein said third connector comprises electromagnetic means.
 17. An extrusion head according to claim 1 further including coupling means on said inner cone of said orifice part and on said outer cone of said orifice part, said coupling means being adapted to be engaged by an auxiliary changing device for removing, connecting and/or transferring said inner and outer cones of said orifice part either separately or jointly.
 18. Extrusion apparatus for plastics extruders comprising a jaw plate, a die head on said jaw plate, said die head having a longitudinal axis, said die head including a base part, an intermediate part and an orifice part, said intermediate part being disposed between said base part and said orifice part, said base part being disposed between said intermediate part and said jaw plate, each of said parts having an inner cone and an outer cone, a first connector connecting said outer cone of said orifice part to said outer cone of said intermediate part, a second connector connecting said inner cone of said orifice part to said inner cone of said intermediate part independently of said first connection such that said inner and outer cones of said orifice part are replaceable on said intermediate part independently of one another, a third connector connecting said outer cone of said intermediate part to said outer cone of said base part, and a fourth connector connecting said inner cone of said intermediate part to said inner cone of said base part independently of said third connector such that said inner and outer cones of said intermediate part are replaceable on said base part independently of one another.
 19. Extrusion apparatus comprising a jaw plate and a die head on said jaw plate, said die head having a longitudinal axis, said die head having an orifice part, an intermediate part and a base part, said orifice part being disposed between said base part and said orifice part, said base part being disposed between said intermediate part and said jaw plate, each of said parts having an inner cone and an outer cone, a first connector connecting said outer cone of said orifice part to said outer cone of said intermediate part, a second connector connecting said inner cone of said orifice part to said inner cone of said intermediate part independently of said first connection such that said inner and outer cones of said orifice part are replaceable on said intermediate part independently of one another, a third connector connecting said outer cone of said intermediate part to said outer cone of said base part such that said inner and outer cones of said intermediate part are replaceable on said base part, coupling means on said inner cone of said orifice part and on said outer cone of said orifice part, and an auxiliary changing device engageable with said coupling means for removing, connecting and/or transferring said inner and outer cones of said orifice part either separately or jointly.
 20. Extrusion apparatus according to claim 19 wherein said auxiliary changing device includes a structure and means enabling said structure to be displaced in the longitudinal and/or transverse director.
 21. Extrusion apparatus according to claim 1 wherein said auxiliary exchange device includes a carriage, exchange means on said carriage, and guide means supporting said exchange means on said carriage. 